Factors influencing the development and course of early dyskinesia, of less than a year's duration, are being studied in a sample of 229 neuroleptic-exposed psychiatric patients. Findings in the first cohort of 100 patients show that unipolar depressions are particularly vulnerable to dyskinesia and show the least improvement on three-year followup. These and other findings will be replicated in a second cohort of 100 patients. Twenty-nine dropouts will be used in analyses of factors relating to the onset of dyskinesia. A five-year extension of the study is proposed which will allow data to be obtained on the course of dyskinesia over a 5 to 14 years period. In addition funds are requested to follow a group of over 200 neuroleptic-exposed depressed patients to determine the rate of occurrence of dyskinesia in this population and to study clinical, treatment and biochemical factors which may influence the development of dyskinesia.